Background: Sperm cryopreservation, used in assisted repro- ductive technology is accompanied with many damages to the cell such as apoptosis. Adding antioxidant to the cryopreserva- tion medium can ameliorate the freezing adverse effects. Silde- nafil citrate (SC) has widespread applications and as an anti- oxidant, has many positive effects on sperm parameters. In this study the effects of SC on the expression of the anti-apoptotic genes in cryopreserved sperms of asthenozoospermic patients were investigated. Materials and Methods: Thirty semen samples were collected from asthenozoospermic patients who had referred to the infer- tility treatment center of Qom University Jihad in 2021. Each sample was divided into 3 groups: Control (fresh); Freeze; and Freeze+ SC (cryo-protectant+ 0.67µM SC). Cryopreservation was performed through the rapid freezing method. In each sam- ple, the expression of the genes Bcl-2 and HSP70 were analyzed using Real-time PCR. The results were reported as fold change (ΔΔCt formula). Data were analyzed statistically using Repeated Measure Analysis and Bonferroni post-hoc test. Results: The expression levels of Bcl-2 and HSP70 genes in- creased significantly (2.64 and 2.85 times, respectively) in the Freeze group compared to the Control group (P=0.000), while the expression levels of these genes increased significantly in the Freeze+ SC group compared to the Control counterpart (4.15 and 2.89 times, respectively) (P=0.000). Conclusion: Adding SC to the sperm cryoprotective medium, increases the expression of the genes Bcl-2 and HSP70, which could be considered as a compensatory response against apop- tosis and oxidative stress induced by freezing.
